Effect of Processing on Release from an Inert, Heterogeneous Matrix

Matrixes containing 40% ephedrine hydrochloride and hydrogenated castor oil are prepared by two processes: (a) compression of a physical mixture and (b) compression of a congealed melt. The release from the melt matrix is slower than from the matrix prepared by compression of a physical mixture. applied pressure on the release profile is studied. For matrixes prepared by both processes as the applied pressure is increased, the release rate is slower; however, this effect is more pronounced for the physical mixture matrix. The effect of comminution of the medicinal compound on release profile is considered. mixture the fastest release occurs from the finer particles suggesting a boundary layer diffusion. In matrixes produced by the melt process as the particle size is decreased, the release is slowed presumably because of an increased tortuosity and more intimate contact between the ephedrine hydrochloride and the hydrogenated castor oil, which produces mass transfer by matrix diffusion.